Impregnated fabric



Jan. 20,1942. P. K. FROLICH 2,270,285

- IMPREGNATED FABRIC I Filed Dec. 31, 1958 2 Shee ts-Sheet 1 2/ MillJan. 20, 1942. P. K. FROLICH IMPREGNATED FABRIC Filed Dec. 31,1933

' 2 Sheets-Shed 2 Patented Jan. 20, 1942 IMPBEQNATED FABRIC reix.Frollch, Westfie'ld, n.1, assignor to Standard Oil Development Company,a corporation of Delaware Application December 31, 1938, Serial No.248,793

2 Claims.

This invention relates to composite fabrics, and particularly to fabricshaving as a part thereof, a polymer formed from olefinic hydrocarbonscondensed directly in and upon the fibres of the fab-ic.

For many purposes it is desirable that fabrics of various sorts shallhave applied thereto suitable coating substances for such purposes aswaterproofing the fabric, filling the interstices between the fibres andthreads of the fabric; for protecting the fabric against the attack ofdestructive elements; for use as a foundation to carry other substances;for pneumatic tire bases, etc., but difficulty has been encountered ingetting a wholly satisfactory incorporation of the coating substanceinto the fabric.

The present invention provides means for polymerizing an olefinic gasdirectly in and upon the fibres and threads of the fabric, to produce asolid coating and polymer of high molecular weight whereby aparticularly thorough, eflicient.

and satisfactory incorporation of the coating material or polymer withrespect to the fabric is obtained.

Bythe procedure of the invention the polymerizable olefinic hydrocarbonand the polymerizing catalyst are applied directly to the fabric, andthe polymerization occurs after the olefin and catalyst are in contactwith the fabric to produce the desired coating of polymerized olefinicsubstance in particularly intimate contact and association with thefibres and threads of a the fabric. Thus an object of the invention isto polymerize an olefinic substance directly upon,

and in the presence of, the fibres of a fabric. This process is alsoadapted to be used in coating and impregnating other fibrous materialssuch as paper, wood, leather, building materials, asbestos, mineralwool, slag wool, cotton, Celotex, Cellophane, viscose, rayons and thelike.

Other objects and details of the invention will be apparent from thefollowing description when read in connection with the accompanyingdrawings wherein Fig. 1 is a diagrammatic representation of apparatusfor polymerizing the olefin upon the fibres of the fabric;

Fig. 2 is a view in section of the embodiment of Fig. 1;

Fig. 3 is an alternative device for practicing the invention;

Fig. is a view in section of the embodiment of Fig. 3; and

Fig. 5 is a detail view of the chill box, spray tube and gutter.

Referring to Figs. 1 and. 2, the fabric which is to be impregnated withpolymer material may be inserted in the form of a roll or spool l withina chill tank 2. The tank 2 may conveniently b cooled by a pool 3 ofliquefied ethylene or other suitable refrigerant in the bottom thereof.The fabric from the roll I is drawn under a guide roll I, placed a shortdistance above the surface of the pool of refrigerant 3 and thencebetween chill boxes 5 and 6. These chill boxes are desirably filled withliquid ethylene at atmospheric pressure thereby setting the temperatureat about 103 C. Alternatively, other refrigerants as desired may beutilized within the chill boxes 5 and G. The fabric is then desirablydrawn over another guide roll 1 above the chill boxes 5 and 5, and fromthe guide roll 1 between squeeze rolls 8 and 9 tea rewind roll H.

A supply of ethylene or other refrigerant is delivered to the chillboxes 5 and 6 by way of the supply pipe i2, and the vaporizedrefrigerant is discharged from the chill boxes 5 and 6 through the pipeM.

In grooves near the bottom of the chill boxes 5 and 6 there are providedperforated spray pipes l5 and it connected to a supply pipe ll throughwhich there is discharged a supply of cooled olefinic gas which largelycondenses in and. upon the fabric l at the temperature maintained between chill boxes 5 and 6. A short distance above the olefinic gas spraypipes 15 and ii there are provided other spray pipes l8 and Iii alsoupon opposite sides of the fabric, through which there is discharged asupply of catalyst which may take the form of gaseous boron trifluoridewhich is absorbed into the fabric and condensed olefinic gases.

In the presence of the boron trifiuoride, the condensed oleflnicmaterial polymerizes rapidly into a high molecular weight, substantiallysaturated, linear type hydrocarbon. The pipes 118 and I9 are desirablyplaced at a point above the point of entrance of the fabric l betweenthe chill boxes 5 and 6 in ,order that the fabric may be chilled to itslowest temperature before the catalyst comes into contact with thepolymerizable olefinic gas charged fabric. It is desirable that asnearly as possible all of the polymerizable olefin shall condense uponfabric i rather than upon the walls of the chill boxes 5 and 6. However,since the olefinic material is practically exclusively in the fabric,relatively little harm is done by a contact of the polymerizableolefinic gas with the walls of the chill boxes 5 and 6. It is furtherdesirable that the spray pipes I I and I! for the catalyst should beplaced a small distance above the spray pipes II and It, in order thatsubstantially all of the oleflnic gases may be condensed into and on thefabric before the catalyst is applied to the oleflnic material andfabric. This is particularly desirable to avoid danger of condensationand polymerization o the olefinic material upon the walls of the chilltanks 5 and 8.

Such portion of the oleflnic gases as are condensed upon the innersurface of the chill boxes 5 and 6 may be caught by gutter members i andreturned to the incoming supply of 'oleflnic gas. It will beobservedthat this arrangement accurately separates from the catalyst anyoleflnic gases which do not condense upon the fabric.

At the low temperature existing in the fabric, the polymerization occursvery quickly to produce a polymer substance in the interstices of thefabric. The physical characteristics of the polymer obtainable aresubject to very accurate control, through the agency of control of thetemperature at which the polymerization occurs. As is well-known. thelower the temperature, especially when the polymerizable olefin is pureisobutylene, the higher the molecular weight of the resulting polymer.That is, if the chill boxes and 5 are maintained at a temperature froml0 C. to 25 C., a polyisobutylene substance is produced upon the fabricwhich may have a molecular weight ranging from 5,000 to 25,000 beingthereby a plastic, somewhat sticky substance. If the temperature of thechill boxes 5 and 8 is kept within the range from -35 C. to 90 C., asolid elastic polymer is produced upon the fabric and in the intersticesof the fabric which may have a molecular weight ranging from 25,000 to250,000.

In some instances, especially when it is desired to incorporate a verylarge amount of polymer material into and onto the fabric, itispreferable to saturate the fabric with the oleflnic material in theliquid form, and for this purpose the embodiment of Figs. 3 and 4 may beutilized. In this form of the invention, a pool 23 of condensed olefinicgas is maintained at the bottom of the chill tank 22 as shown, andthefabrlc 2| is carried under the guide roll 24 and upward between thechill boxes 25 and 25 in a manner closely similar to that previouslydescribed. However, only a single pair of spray pipes 28 and 29 isprovided, through which the catalyst is discharged onto theolefin-carrying fabric. In this embodiment, the catalyst used may begaseous boron trifluoride as before described or it may be a solution ofaluminum chloride in ethyl chloride. In either event, the polymerizationtakes place in and on the fabric between the chill boxes.

In still another embodiment of the invention, a pool of liquid catalystsolution 23 may be maintained at the bottom, of the chill tank 22 andthe fabric 2| may be passed first through the pool of liquid catalyst 23such as aluminum chloride dissolved in ethyl chloride, or borontrifluoride dissolved in liquefied ethylene or other of theFriedel-Craft type of catalysts. The catalyst-carrying fabric is thendrawn upward under the roll 24 between the chill boxes 25 and 26 asbefore, past the spray tubes 28 and 29 through which the olefinic gas isdischarged. The gas condenses upon the fabric and polymerizes therein inthe presence of the catalyst.

The polymer-coated fabric may then be drawn over the roller 21 between apair of exit rollers SI and 32 which serve to limit the egress of anyunpolymerized oleflnic gases from the container 22 and by a wringeraction may be caused to I return a substantial portion of the catalystsolution to the bottom of the container 22. It is desirable that thecatalyst solution 23 be reduced to a minimum temperature, andaccordingly a substantial portion of liquid ethylene may be added atatmospheric pressure to the solution 23 to maintain the entire tank 22and all its contents at the desired low temperature.

The eiliuent gas which may comprise in large part the refrigerantethylene, and in further part may comprise unpolymerized olefinic gas,is discharged from the container 22 through an exit pipe 33.

It is not necessary that pure isobutylene be utilized for thepolymerizable substance. In stead, a mixture of isobutylene andbutadiene may be utilized. This mixture is preferably made in the ratioof 70-90 parts of isobutylene and 30-10 parts of butadiene. The mixturemay be condensed into a pool of olefinic liquid 23 at the bottom of thechill tank 2 and the fabric dipped into the pool 23 of the liquefiedmixed oleflns. When saturated with the olefins, the fabric may be drawnbetween the chill plates 25 and 26, and the catalyst discharged throughthe spray pipes 28 and 29 onto the fabric. For this polymerization it ispreferable to use the solution of aluminum chloride in ethyl chloridepointed out in the previously described embodiment. Other catalysts may,however, be utilized.

This type of polymerization may be performed from the gaseous phascincommon with the previously described form, by the use of two pairs ofspray tubes, the lower pair being utilized to discharge onto and intothe fabric a gaseous mixture of the desired olefins, which are thencondensed by the abstraction of the heat of vaporization into the chilltanks 25 and 26 and the catalyst is sprayed onto the fabric from thesecond pair of spray tubes. If a small amount only of polymer is to beincorporated into the fabric, it

' is desirable that a substantial portion of the olefinic gases shall beabsorbed into the fabric before polymerization, in order to permit ofthe completion of the polymerization. When larger quantities of thepolymer are to be laid down upon the fabric a portion of thepolymerization may occur simultaneously with the condensation of thematerial into the fabric although this latter arrangement is lesssatisfactory since it does not insure permeation of all of the polymerinto the fabric as effectively as is possible when the olefinic materialpenetrates into the fabric before the polymerization reaction begins.

It is to be noted that the polymerization reaction is exceedinglysensitive to poisoning by in-.

cluded substances, and it has been found that a high molecular weightpolymer is obtainable only when the polymerization is conducted withexceedingly pure oleflnic gas, and a very pure catalyst. Even smalltraces of a wide range of substances act as catalyst poisons, and eitherprevent the polymerization entirely, or reduce it to such a low amountas to produce nothing but a low molecular weight polymer which is merelya liquid, viscous oil. In contrast to the active poisoning effectresulting from the presence of most auxiliary substances, it is foundthat cellulosic materials are substantially free from poisoning efiectupon the catalytic polymerization reaction; and that the polymerizationoccurs just as readily in the presence of cellulose material as in theabsence of impurities of all sorts.

Furthermore. it is found that the polymer is exceedingly closelyattached to the cellulosic fibres; and far more closely attached than ispossible with any of the calendering or dipping in a cellulose fibreoccur in micelae" which are oriented in the fibre in a definite manner.It is believed that. whether interpolymerization between the cellulosemolecule and olefinic gas occur or not, a substantial penetration of thepolymer into the micellar structure of the cellulose occurs, therebyproducing a far more intimate interrelationship between the celluloseand olefinic polymer than is possible by any other procedure.

In any event the resulting fabric shows all of the resistance to acid,alkali, oxygen and other chemical action which is characteristic of thepolymer per se, and the cellulose in the fabric appears to be far morethoroughly protected than is possible with any other type of coating orimpregnating treatment.

Furthermore, the amount of polymer present is readily determined by therate at which the polymerizable olefinic gas is delivered into thefabric, or the amount of liquefied olefinic material which is chargedinto the fabric before polymerization. The quantity may be controlledbetween an amount sufilcient to produce a fully impervious sheet closelyanalogous to balloon cloth, or a fully impregnated tire cord fabricwhich is fully covered including a relatively thick surface layer, downto an amount so small as to bev practically imperceptible to touch orobservation, but sufficient to give the fabric a new and valuablespringycharacteristic, and still provide a pronounced and valuableprotection against oxidation or other chemical reactions of thecellulose fibre.

It is well known that the isobutylene polymer, especially when producedto have a molecular weight ranging from. 27,000 to 300,000, isexceedingly resistant to atmospheric oxygen; to oxygencontainingsolvents, to acids, to alkali, and to heat if not excessive, andaccordingly a fabric having very greatly increased wear-resistingproperties is obtainable.

These qualities are particularly characteristic of the polymer producedfrom the mixture of isobutylene and butadiene which when sulfurized asdescribed below has a resistance to heat, t.

abrasion, and to fiexure which is outstandingly superior to any otheranalogous substances. That is, it is possible to iron the fabric withoutinjury to the polymer coating. Furthermore, the material does notoxidize in air to become stiff, brittle and harsh; and the presence ofthe polymer material provides a very valuable lubricating effect betweenthe fibres of the fabric.

A particularly valuable product is obtainable when the gas dischargedthrough the pipes ll and I2 consists of 80% to 90% isobutylene and from20% to butadiene. It is of course desirable that-the catalyst be removedfrom the polymer material. This is readily accomplished by washing andkneading the material in water or alkaline solution or by other methodswhich will be obvious to workers in the field. This material can besulfurized, and a sufficient amount of sulfur for'the reaction may beincorporated into the fabric either from suspension or solution in theliquid catalyst, if such is used, or by sprinkling the sulfur in a formsuch as fiowers of sulfur upon the fabric after the polymerizationprocedure. The sulfurization may then be completed by heating the fabricand incorporated polymer to a temperature in the neighborhood of 140 C.for the required length of time of several hours.

The procedure of the invention is particularly advantageous forreinforcing fabric used in automobile tires, especially when the treadis produced from the same polymer of isobutylenebutadiene since underthese circumstances a particularly thorough and effective incorporationof the polymer into the fabric is obtainable; and since the polymer is alinear chain hydrocarbon, it provides a very valuable lubricating effectbetween the flbres of the fabric which greatly lengthens the life of thefabric and tire produced therefrom and reducesthe rate of wear inservice.

Theabove-described embodiments are presented as incorporating thepolymer material into a cotton fabric. It is not, however, limited tospun and woven cotton fabrics since the reaction proceeds equallysatisfactorily with linen fabrics, which are chemically cellulose inslightly different physical form from cotton fibres. The polymerizationprocedure is similarly adapted to the impregnation of woolen fabricswith polymer in any desired amount; and to the impregnation of silkfabrics. It is particularly advantageous for this purpose, since a smallamount of the polymer provides a very valuable stiffening, strengtheningand wear-reducing effect which is far superior to the practice ofweighting by means of tin. The amount of polymer may be just sufficientto coat the silk filaments without noticeably modifying the appearance,and modifying the feel of the silk only to the extent of slightlyincreasing the springiness or stiffness; or larger amounts may beincorporated to give considerably increased springiness and elasticity,up to the point where a fully waterproof fabric is produced. The processis equally applicable to rayon, either of the viscose type, thecuprammonium type, or the denitrifled Chardonnet type, these being allregenerated cellulose or hydrocellulose, and the procedure is similarlyeffective. The procedure is equally applicable to the celanese type ofartificial silk which is spun cellulose acetate. The procedure is alsoapplicable to felts, whether formed of fur or wool; and to paper aswell. The procedure is also applicable to sheet Cellophane for theproduction of a strongly adherent waterproof and wear-resistant coatingupon one or both surfaces of the Cellophane. The procedure is readilyapplicable to the very thinnest fabrics, such as tulle or veiling orgeor- There is thus produced by the process and apparatus of theinvention a new type of fabric in which there is polymerized asubstantial quantity of an olefinic substance to form a. high molecularweight polymer which is extremely thoroughly interspersed between thefibres oi the fab.- ric.' When so dispersed the polymer provides anamount of protection for the fibres which is of a wholly new order ofmagnitude both by virtue of the fact that the fibres are sheathed withchemically inert and resistant polymer in a fashion not previouslypossible; and by virtue of the lubricating effect of the polymer betweenthe fibres of the fabric. The invention thus provides a process forincorporating polymer into a fabric; a machine for facilitating theincorporation of the polymer into the fabric; and a new materialcomprising a fabric having an oleflnic polymer exceedingly intimatelyincorporated into the I fibres thereof.

While there are above disclosed but a limited number of embodiments ofthe structure of the invention. it is possible to produce still otherembodiments without departing from the inventive concept hereindisclosed, and it is therefore desired that only such limitations beimposed upon the appended claims as are stated therein or required bythe prior art.

The invention claimed is:

1. The process of producing a high molecular weight heteropolymer ofisobutylene and butadiene in the interstices of a fabric which comprisesthe steps of charging the fabric with a mixture of isobutylene andbutadiene, and treating' the charged fabric with a Friedel-Crafts typecatalyst at a temperature below 10 0., thereby polymerizing the mixtureof isobutylene and butadiene to a high molecular weight polymer in theinterstices of the fabric.

2. The process of producing a high molecular weight heteropolymer ofisobutylene and butadiene in the interstices of a fabric which com-vprises the steps of charging the fabric with a mixture of isobutyleneand butadiene, and treating the charged fabric with a Friedel-Craftstype catalyst comprising a solution of aluminum chloride in anon-complex-forming solvent which is liquid below 10 C., therebypolymerizing the mixture of isobutylene and butadiene to a highmolecular weight polymer in the interstices of the fabric.

PER K. FROLICH.

